Al Jihad, N. G., Fatih Mufadhdhal, M., & Aprianto, R. . (2026). Design and Development of a Countdown Timer System in the Passenger Pickup and Drop-off Area Based on Ultrasonic Sensor. Jurnal Perintis: Pengembangan Riset Inovatif Teknik, Teknologi, Dan Sains, 2(2(Maret-April), 83-91. https://ejournal.pktj.ac.id/index.php/perintis/article/view/117